Andrew LaMotte 2010 vector digital data Digital Data Series DDS-576 Reston, VA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?mddc_indexes These data sets represent 23 geographic 5-minute indexes for the counties of Maryland, one 2 1/2-minute index for Washington D.C., and 1-mile square index for Baltimore City. There are 25 vector polygon data sets covered by this metadata report. These data sets were created to establish local well names for groundwater sites within Washington D.C., Baltimore City, and the counties of Maryland. This follows the previously established well-naming procedure adopted and used by the U.S. Geological Survey from paper maps. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the data set in nonproprietary form, as well as in ARC/INFO format, this metadata file may include some ARC/INFO-specific terminology. 2010 publication date Complete None planned -76.916667 -76.333333 39.250000 38.666667 None 5-minute index 2 1/2-minute index 1-mile index inlandwaters None Allegany County Anne Arundel County Baltimore County Baltimore City Calvert County Caroline County Carroll County Cecil County Charles County Dorchester County Frederick County Garrett County Harford County Howard County Kent County Montgomery County Prince George's County Queen Anne's County Saint Mary's County Somerset County Talbot County Washington County Wicomico County Worcester County Washington, D.C. Maryland United States None None Andrew LaMotte U.S. Geological Survey Geographer mailing and physical address

5522 Research Park Drive

Baltimore Maryland 21228 USA 443-498-5549 443-498-5510 alamotte@usgs.gov http://water.usgs.gov/GIS/browse/mddc_indexes.jpg Groundwater Site Identification Indexes for Washington D.C., Baltimore City, and the Counties of Maryland JPEG Microsoft Windows 2000 Version 5.2 (Build 3790) Service Pack 2; ESRI ArcCatalog 9.3.1.3500 Random checks of data were completed by author and reviewers. Each index was mapped and labelled for visual inspection. Bennett, Robert R. Meyer, Rex R. 1952 map Bulletin Bulletin 4, Plate 1 Baltimore, MD State of Maryland Board of Natural Resources, Department of Geology, Mines and Water Resources Paper map (plate 1) 1952 publication date MGS Bulletin 4 Plate 1 displayed the 1-mile city grid and origin. The 5-minute county data sets were created using the fishnet subcommand of the generate command in ArcGIS workstation. Fishnet requires an origin (x,y), Y-axis (x,y), cell size (x,y), and numbers of rows and columns (n,n). Parameters for each county are: Allegany County origin: -79.083333333,39.416666666 Y-Axis: -79.083333333,39.5 Cell Size: 0.083333333,0.083333333 rowcol: 4,10 Anne Arundel County Origin: -76.916666666, 38.666666666 Y-axis: -76.916666666, 38.75 Cell size: 0.083333333, 0.083333333 Rows, columns: 7, 7 Baltimore County origin: -76.916666666,39.166666666 Y-Axis: -76.916666666,39.25 Cell Size: 0.083333333,0.083333333 rowcol: 7,8 Calvert County origin: -76.75,38.25 Y-Axis: -76.75,38.333333333 Cell Size: 0.083333333,0.083333333 rowcol: 7,5 Caroline County origin: -76.083333333,38.583333333 Y-Axis: -76.083333333,38.666666666 Cell Size: 0.083333333,0.083333333 rowcol: 7,5 Carroll County origin: -77.333333333,39.333333333 Y-Axis: -77.333333333,39.416666666 Cell Size: 0.083333333,0.083333333 rowcol: 5,7 Cecil County origin: -76.25,38.05 Y-Axis: -76.25,39.666666666 Cell Size: 0.083333333,0.083333333 rowcol: 5,6 Charles County origin: -77.333333333,38.166666666 Y-Axis: -77.333333333,38.25 Cell Size: 0.083333333,0.083333333 rowcol: 7,9 Dorchester County origin: -76.416666666,38.083333333 Y-Axis: -76.416666666,38.166666666 Cell Size: 0.083333333,0.083333333 rowcol: 8,9 Frederick County origin: -77.75,39.166666666 Y-Axis: -77.75,39.25 Cell Size: 0.083333333,0.083333333 rowcol: 7,8 Garrett County origin: -79.5,39.166666666 Y-Axis: -79.5,39.25 Cell Size: 0.083333333,0.083333333 rowcol: 7,7 Harford County origin: -76.583333333,39.25 Y-Axis: -76.583333333,39.333333333 Cell Size: 0.083333333,0.083333333 rowcol: 6,7 Howard County origin: -77.25,39.083333333 Y-Axis: -77.25,39.166666666 Cell Size: 0.083333333,0.083333333 rowcol: 4,7 Kent County origin: -76.333333333,39.0 Y-Axis: -76.333333333,39.083333333 Cell Size: 0.083333333,0.083333333 rowcol: 5,7 Montgomery County origin: -77.583333333,38.916666666 Y-Axis: -77.583333333,39.0 Cell Size: 0.083333333,0.083333333 rowcol: 6,9 Prince George's County origin: -77.166666666,38.5 Y-Axis: -77.166666666,38.583333333 Cell Size: 0.083333333,0.083333333 rowcol: 8,6 Queen Anne's County origin: -76.416666666,38.833333333 Y-Axis: -76.416666666,38.916666666 Cell Size: 0.083333333,0.083333333 rowcol: 6,8 Saint Mary's County origin: -76.916666666,38.0 Y-Axis: -76.916666666,38.083333333 Cell Size: 0.083333333,0.083333333 rowcol: 7,8 Somerset County origin: -76.083333333,37.833333333 Y-Axis: -76.083333333,38.916666666 Cell Size: 0.083333333,0.083333333 rowcol: 6,7 Talbot County origin: -76.416666666,38.5 Y-Axis: -76.416666666,38.583333333 Cell Size: 0.083333333,0.083333333 rowcol: 6,7 Washington County origin: -78.416666666,39.25 Y-Axis: -78.416666666,39.333333333 Cell Size: 0.083333333,0.083333333 rowcol: 6,12 Wicomico County origin: -76.0,38.166666666 Y-Axis: -76.0,38.25 Cell Size: 0.083333333,0.083333333 rowcol: 5,9 Worcester County origin: -75.666666666,37.916666666 Y-Axis: -75.666666666,38.0 Cell Size: 0.083333333,0.083333333 rowcol: 7,8 The index created from the fishnet command was then converted into a polygon coverage through the build command and the geographic projection was defined. Rows (row) were attributed with uppercase letters and columns (col) were attributed with lowercase letters in alphebetic order begining at the top left in both cases. The attribute rowcol was created by concatenating row and col attributes. The final attribute value (index) was created by concatenating the two-letter county abbreviation with the rowcol attribute. Polygons not containing any part of the county were deleted. A labeled map was printed and compared to original drawings for verification. The 1-mile Baltimore City data set was created by establishing the origin of the grid. This is found in Bennett and Meyer's (1952) Geology and Ground-Water Resources of the Baltimore Area, Plate 1, Location of water wells in Baltimore. The origin of the grid coincides with the southwest street corner of MT Vernon Place and Charles Street and it's state plane (NAD27) coordinates are Easting 90880, Northing 533400, in feet. With a known origin, a spreadsheet of grid coordinates was developed by increments of 5,280 (feet in 1 mile). These coordinates were then buffered by 5,280 feet to produce merged polygons that make up the Baltimore City index. The index grid was then attributed according to distances from the origin (1N3W, for example) and excess cells falling outside of the city were deleted. The 2 1/2-minute Washington, D.C. index grid's origin was created by using the latitude and longitude of the lower left corner of the Alexandria, VA 7.5-minute USGS Topographic Map. The fishnet input values were: Washington D.C. 2.5 minute grid origin: -77.25,38.75 Y-axis: -77.25,38.791666666 Cell Size: 0.041666666,0.041666666 rowcol: 8,9 2010 Vector Complete chain 84 Label point 35 GT-polygon composed of chains 35 Point 4 38.666667 76.916667 Decimal degrees North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 aa_index.pat Polygon attribute table ESRI FID Sequential unique whole numbers that are automatically generated. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Coordinates defining the features. AREA Area of feature in internal units squared. ESRI Positive real numbers that are automatically generated. PERIMETER Perimeter of feature in internal units. ESRI Positive real numbers that are automatically generated. AA_INDEX# Internal-defined feature number. ESRI Sequential unique whole numbers that are automatically generated. AA_INDEX-ID Internal-defined feature number. ESRI Sequential unique whole numbers that are automatically generated. COUNTY Two letter abbreviation for county U.S. Geological Survey Sequential unique whole numbers that are automatically generated. ROWCOL Two letter code signifying ROW (uppercase) and Column (lowercase) U.S. Geological Survey Sequential unique whole numbers that are automatically generated. INDEX The four letter prefix of a local well name determined by the uppercase two letter county abbreviation followed by the well's location within the county index described by the uppercase letter for row and the lowercase letter for column, separated from the county abbreviation by a space. U.S. Geological Survey Sequential unique whole numbers that are automatically generated. U.S. Geological Survey Ask USGS -- Water Webserver Team mailing address

445 National Center

Reston Virginia 20192 USA 1-888-275-8747 (1-888-ASK-USGS) http://water.usgs.gov/user_feedback_form.html Downloadable Data Although this data set has been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of these data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Arc export .e00 file (zipped) 1 Arc export .e00 file (zipped) Winzip 13kb http://water.usgs.gov/GIS/dsdl/mddc_indexes.zip Arc Shape.shp file (zipped) 1 Arc Shape file (zipped) Winzip 13kb http://water.usgs.gov/GIS/dsdl/mddc_indexes_shape.zip Arc Geodatabase.dbf file (zipped) 1 Arc Geodatabase file (zipped) Winzip 13kb http://water.usgs.gov/GIS/dsdl/mddc_indexes_gdb.zip None. This data set is provided by the USGS as a public service. 20110224 U.S. Geological Survey Ask USGS -- Water Webserver Team physical address

445 National Center

Reston Virginia 20192 USA 1-888-275-8747 (1-888-ASK-USGS) http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+mddc_indexes FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998